Long-term survival estimates of cast gold inlays and onlays with their analysis of failures

The aim of the present study was to assess the clinical behaviour of cast g old restorations with respect to define a gold control against current and future ceramic and composite restorations. The study sample included 50 pat ients with 303 cast gold restorations. All restorations were cemented with a non-adhesive technique. A total of 303 restorations were evaluated clinic ally and radiographically using modified United States Public Health Servic e criteria. Restorations recorded as having an A- or a B-rating were define d as successful. Of the 303 restorations, 42 were judged as failures, which resulted in a failure rate of 13.8% for a mean observation time (+/- s.d.) of 18.7 (+/-9.5) years. The estimated Kaplan-Meier survival rates (+/- s.e .) were 96.1% (+/-1.1%) at 10 years, 87.0% (+/-2.2%) at 20 years and 73.5% (+/-5.4%) at 30 years. In total, biological reasons were counted 25 times i n comparison to 17 technical reasons for those 42 failed cast gold restorat ions, with 17 secondary caries (40%) as the most common biological reason a nd with 13 retention losses (31%) as the most common technical reason. The endodontically treated tooth was exclusively identified as a risk factor. T he restoration type (inlay versus onlay) did not influence the survival rat e.